I did this recently. Had a hard drive from a dead Gateway machine.
VMware can set up a virtual machine from an image file, but not a regular hard disk and file system. I used Acronis True Image. Ghost works and so do a few others. I hooked up the drive using a USB adapter and created an image (a .tib file).
Then I used the VMware converter program (free download) to transform that image into a VM. Worked great.